Sen. Rob Portman is considering a bid for National Republican Senatorial Committee chairman, a post his colleagues have asked him to consider running for.

However, the Ohio Republican has made no decisions, a source close to Portman told Roll Call this afternoon. Politico first reported news of Portman's interest in running the NRSC.

The speculation comes as Senate Republicans wallow in the apparent loss of two seats last night. Democrats defended twice as many seats as Republicans in 2012, and at the start of the cycle, the GOP was expected to pick up seats this cycle — perhaps even win the majority.

Sen. Marco Rubio (R-Fla.) has declined his colleagues' overtures to serve as NRSC chairman for the 2014 cycle, according to an aide. Senate Minority Leader Mitch McConnell (R-Ky.) asked Rubio to take the helm of the beleaguered committee, but he declined, according to Real Clear Politics. Roll Call independently confirmed his refusal.

The current chairman, Sen. John Cornyn (R-Texas), cannot run the committee for a third term and is running for Republican Whip. His seat is up for re-election in 2014.